Condensed melamine phosphates

Abstract

This invention relates to a novel process for the preparation of condensed melamine phosphates, and to melamine pyrophosphate prepared by this process having improved thermal stability as a flame retardant.

What is claimed is:  
     
       1. A process for preparation of a melamine condensed phosphate comprising the steps of: 
       a) contacting a solution of an alkali metal condensed phosphate with an acidic ion exchange resin at a temperature of 0°C to ambient to yield condensed phosphoric acid, and  
       b) adding the condensed phosphoric acid to a slurry or suspension of melamine at a temperature of 0°C to ambient to yield the corresponding melamine condensed phosphate.  
     
     
       2. The process of claim  1  wherein the alkali metal condensed phosphate is tetrasodium pyrophosphate or tetrapotassium pyrophosphate. 
     
     
       3. The process of claim  1  wherein the melamine condensed phosphate is melamine pyrophosphate. 
     
     
       4. The process of claim  3  wherein the molar ratio of alkali metal condensed phosphate to melamine is 0.5 to 1.